Opposite effects of polyols on antibody aggregation: thermal versus mechanical stresses.

PURPOSE

To investigate the physical stability of antibody-polyol formulations under thermal and mechanical stresses.

METHODS

mAb-U was analyzed in buffer, trehalose, sucrose, glycerol and ethylene glycol solutions at pH 7.0. T(m1) of mAb-U was determined using DSC. Thermal stress studies were performed by incubating mAb-U-polyol solutions at 40°C (2 months), 50°C (3 weeks) and 65°C (5 days). Mechanical stress studies were conducted by shaking mAb-U-polyol solutions at 200 rpm for 5 days at 25°C.

RESULTS

Trehalose and glycerol increased the T(m1) of mAb-U, whereas ethylene glycol decreased it. The trend observed in the order of increasing aggregation of mAb-U after thermal stress (40°C and 50°C) was buffer = trehalose = sucrose<glycerol<ethylene glycol. A similar trend in aggregation was observed for 65°C studies. An inverse relationship was observed in aggregation trends upon exposure to mechanical and thermal stresses.

CONCLUSIONS

Preferentially excluded polyols increase the conformational stability of proteins but also increase their chemical potential in the solution phase. This increase in free energy can promote precipitation and interfacial adsorption of a protein as these reactions result in a decrease in its free energy. Therefore, addition of polyols can be destabilizing for the physical stability of aqueous protein formulations.